Drill assembly

ABSTRACT

A drill assembly particularly suitable for use in building construction. The assembly includes an upright framework supporting a vertically moveable carriage. A rotatable, first threaded rod extending transversely between two forwardly projecting, horizontal arms of the carriage carries a threaded traveling member to which is attached a forwardly projecting horizontal shaft. A drill motor connected with the forward end of the shaft may be selectively pivoted between positions in which the drill shaft is horizontal and vertical. The carriage includes support members which bear slidably against the upper and lower surfaces of the shaft, thus providing a vertically stable support for the drill. In addition, a second threaded rod parallel to the first carries an aligned second traveling member also secured to the shaft. The quadrilateral arrangement of two rods and two traveling members insures that the drill is provided with stable lateral support also.

United States Patent 1191 Mee 1451 July 23,1974

2,127,066 8 1938 McCullough 2,832,567 4 1958 3,313,355 4/1967 3,314,725 4/1967 173 43 x DRILL ASSEMBLY [76] Inventor: Robert L. Mee, 3600 Paradise Rd.,

Apt. 94, Las Vegas, Nev. 89109 [22] Filed: June 18, 1973 [21] Appl. No.: 371,171

[52] Cl; 173/43, 173/160 [51] Int. Cl. E21c 5/02, E21c 5/11 [58] Field of Search 173/39-44, 173/160; 74/841 [56] References Cited UNITED STATES PATENTS 1,072,256 I '9/1913 Piccone etal. 173 43 x 1,838,459 12/1931 Smith etal' 173/16OX Primary Exami'ner--David H. Brown Attorney, Agent, or F irmFu lwider Patton Rieber Lee D W & Utecht ABSTRACT A drill assembly particularly suitable for use in building construction. The assembly includes an upright framework supporting a vertically moyeable carriage.

' A rotatable, first threaded rod extending transversely between two forwardly projecting, horizontal arms of the carriage carries a threaded traveling member to which is attached a forwardly projecting horizontal shaft. A drill motor connected with the forward end of the shaft may be selectively pivoted between positions in which the drill shaft is horizontal and vertical. The

carriage includes support members which bear slidably against the upper and lower surfaces of the shaft,'

thus providing a vertically stable support for'the drill. In addition, a second threaded rod parallel to the first carries an aligned second traveling member also se-- cured to-the shaft. The quadrilateral arrangement of two rods and two traveling members insures that the drill is provided with stable lateral support also;

9 Claims, 2 Drawing Figures DRILL ASSEMBLY BACKGROUND OF THE INVENTION This invention relates to a drill assembly of the type used for drilling through masonry or other building structures. In particular, it "relates to an assembly wherein a drill mounted on a rigid framework is provided with a capability to traverse vertically and laterally to position the drill shaft.

In the construction of buildings, it is frequently necessary to bore a large number of aligned holes through wall and masonry structures, in both vertical and horizontal directions, for the installation of piping, conduit runs, electrical cables-rand the like. Such drilling operations are frequently performed utilizing manually held portable drills with either a double handle or a shoulder brace. However, the use of manually supported drills can be very tiring. Problems can also arise in accurate alignment of holes clue to the ease with which a manually held drill can deviate from the desired direction.

To avoid these disadvantages, it has previously been known to utilize a supporting frame on which the drill is mountedfor vertical and transverse motion, thus relieving the operator of the need to support it manually. One such prior device comprises a generally rectangular frame havingtwo vertical pillars and a transverse cross bar, extending between them, mounted for vertical movement relative to the frame by a rack and pin ion drive. The drill is carried by the cross bar extending forwardly from it toward the workpiece. In an additional refinement, the drill unit may be moved transversely along the support member by another rack and pinion connection, thuspermitting the drill position to be selectively varied in both vertical and transverse directions relative to the supporting frame. 7

A prior device of the type described may, however,

' prove unsatisfactory for drill work in building construc- SUMMARY, OF THE lNVENTlON A drill assembly constructed in accordance with the present invention is intended to permit the drilling of holes in building construction with improved precision. This result is achieved by utilizing a supporting framework and a vertically moveable carriage for the drill unitwherein the drill is provided with a particularly stable mounting in which the freedom of the drill to displace or twist out of position relative to the framework is substantially prevented. Structure for this purpose includes portions of the carriage which extend outwardly from the frame towards the drill and stabilize the drill against vertical displacement and additional structure which supports the drill against lateral displacement also so that an accurate drilling position is maintained.

In more detail, a drill assembly, according to the invention, includes an upright, rigid framework adapted to rest upon the ground. A carriage is connected with the framwork for vertical relative motion and includes two generally horizontal arms connected in spaced opposedrelation extending in a first direction, forwardly from the frame. A threaded first rod, rotatably connected at its ends with the arms, extends horizontally between them in a transverse, second direction which is perpendicular to the first direction. A traveling member threadedly engagesthe first rod and is moveablealong it between the arms. The traveling member carries a horizontal shaft extending forwardly in generally horizontal disposition. A drill, which includes a drill motor and a drill shaft extending from the drill motor, is connected by a connecting member to the forward extremity of theshaft. The drill is thus carried'by the shaft. To stabilize the drill against vertical motion relative to the carriage, while enabling horizontal transversing when the rod is rotated, two transverse support members connected with the arms extending between them, slidingly contact the upper and lower surfaces of the shaft adjacent its forward extremity.

In addition, the shaft carrying the drill is also supported against inadvertent lateral displacement. For this. purpose, a second threaded rod rotatably connected with the arms is positioned in parallel relation to the first threaded rod spaced forwardly of it. A second traveling member, threadedly connected to the second rod and aligned transversely with the first traveling member, is fixedly connected to'the shaft. A drive train connects the first and second rods for coordinating their rotation so that as the traveling members move along the rods between the arms, they maintain their transverse alignment carrying the shaft with them. The spaced support along the length of the shaft provided by the two traveling members carried on the two Y threaded rods stabilizes the drill unit against lateral displacement relative to the carriage.

It will be appreciated that the arrangement described in which the carriage stabilizes the drill against vertical and lateral displacement enables the drill position to be maintained in accurate relation to thefr'ame so that holes may be drilled with precision once the desired alignment has been set.

To cause vertical motion of the carriage relative to the frame, a third threaded rod, extending vertically, is

connected with the frame adjacent its upper and lower.

ends. The third threaded rod passes through a transverse strut connected with the carriage, which has an internal threaded opening engaging the rod. Selective rotation of the rod by a reversible motor in opposite directions causes raising and ative to the frame.

During this vertical motion, the carriage is guided relative to the frame. For this purpose, the frame includes two vertical, parallel pillars spaced on opposite sides of the rod which function as tracks for two confonningly shaped guide shoes secured to the carriage. The guide shoes ride on the surfaces of the pillars and maintain the horizontal disposition of the carriage while guiding its vertical motion.

Additional rigidity for the pillars is provided by two horizontal legs which extend rearwardly from the lower ends of the pillars, resting on the ground. Bracing connected to the pillars, on an opposite side from the carriage, extends from the upper ends of the pillars down lowering of the carriage rel-' to the legs, and imparts rigidity to the structure thereby contributing to the maintenance of a stabilized trajectory for the drill shaft.

BRIEF DESCRIPTION OF THE DRAWINGS A drill assembly constructed in accordance with the preferred embodiment of the invention is illustrated in the accompanying drawings in which:

FIG. 1 is a perspective view of a drill assembly constructed in accordance with the preferred embodiment of the invention; and

FIG. 2 is a cross-sectional top view of the drill assembly shown in FIG. 1 taken along the lines 2-2 therein.

DETAILED DESCRIPTION The drill assembly (FIG. 1) includes an upright, generally rectangular framework 2 supporting a vertically moveable carriage 4 which carries a drill unit comprising a drill motor 6 having a drill shaft 8 provided with a cutting tool 10 The carriage 4, as will be described more fully hereinafter, contributes very significantly to the stability of the cutting tool and drill shaft during operation by stabilizing the drill unit against lateral and vertical displacement during drilling, thereby permitting precision drilling in the building applications for which the tool is primarily intended. v I

As has been mentioned earlier, in the backgroundto the invention, it has previously been known to support a drill on a cross bar moveable vertically on a frame. However, the additional stabilizing structure of the present invention provided by the .carriage 4 is intended to obviate the disadvantages resulting from the earlier devices. 4

Thus, the carriage 4 of the present invention includes two side arms 12 extending in a forward direction from the frame, in spaced parallel relation to each other. The arms 12, intermediate their ends, rotatably mount a first threaded rod 14 which may be rotated by handwheels 16 connected at its ends outside the arms 12. The threaded rod 14 carries a first traveling member 18 which is an internally threaded, rectangular block. The member'l8 traverses from one end of the rod 14 to the other between the arms as the rod is rotated. A horizontal shaft 20 is carried by the traveling member 18 and extends forwardly from it beyond the forward extremities of the arms 12. The shaft 20 has a hollow internal bore which slidingly receives a horizontal axle 22 fixedly secured to the drill motor 6. The motor 6 may be rotated through 360 through positions in which the drill shaft 8 extends vertically up or down, or horizontally to the right or left, or at any intermediate inclination. It may be locked in any position by a clamp nut 24 extending through a threaded opening in the shaft 20 and bearing against the exterior of the axle 22.

To support the drill motor against vertical displacement relative to the carriage, thereby insuring accurate drill positioning, a transverse horizontally slotted bar 26 extends between and is secured to the forward extremities of the side arms 12. The upper-and lower surfaces defining the horizontal slot in the bar 26 are close to the drill motor and constitute upper and lower support members preventing vertical displacement of the shaft adjacent its free extremity so that vertical displacement of it relative to the carriage 4 is substantially prevented.

In addition, structure is also provided to prevent lateralmisalignment of the drill unit relative to the carriage. This structure includes a second threaded rod 28 (FIG. 2) having its ends rotatably mounted on the side arms 12, positioned in parallel relation to the first .threaded rod 14 spaced forwardly from it. A second traveling member 30, threadedly engaging the second rod 28, is fixedly secured to the shaft 20 in transverse alignment with the first traveling member 18. The spaced apart connections provided by the traveling members 30 and 18 to the shaft 20 and their threaded connections to the first and second threaded rods 14 and 28 provide a rigid quadrilateral structure substantially preventing any lateral misalignment of the shaft 20 relative to the carriage and, hence, of the drill unit carried by the shaft.

It will be appreciated that the structure thus far described substantially eliminates misalignment of the drill unit relative to the carriage 4 so that precision of I alignment may be maintained. In this manner, the disadvantages of a motor mounted on a cross bar on a frame, associated with certain prior art devices, is

avoided.

To insure that the transverse alignment between the first and second traveling members 18 and 30 is maintained as the traveling members move laterally between the side arms, a drive train 32, comprising two sprockets and a chain, connects the threaded rods at their ad- 'jacent extremities to insure that they rotate in such timed relation as to insure that the traveling members do not move out of alignment.

The previously mentioned framework 2 includes a vertical, rectangular front frame 36 comprising two vertical, upright pillars38 of rectangular cross-section,

connected at their upper and lower extremities by hori-.

zontal cross members 40. Extendingvertically and centrally between the pillars 38 is a vertical, third threaded rod 42 having its upper and lower ends rotatably mounted in bearing units 43 connected to the forward surfaces of the upper and lower cross members40. The

, rod 42 is selectively rotated in opposite directions by a reversible electric motor 44 mounted on the upper cross member and connected to the threaded rod 42. In addition, the rod may be turned manually, for fine adjustment, by a finger controlled nut 46. The threaded rod 42 passes through a correspondingly threaded sleeve 50 which is fixedly connected to the carriage 4 by a cross bar 52 that extends between and is fixedly secured to the side arms 12 adjacent their rear extremities. Thus, as the rod 42 rotates, it moves the sleeve 50 up and down the frame carrying the carriage 4 with it through the medium of the connecting cross bar 52.

To guide the carriagein its vertical motion, it is provided with vertical shoulders 54 and 56 secured to the sidearm's 12 projecting outwardly therefrom in sliding, abutting contact with the forward and rear surfaces of the pillars 38. It may be considered that the shoulders 54 and 56 and the intervening surface of the side arms 12 together constitute guide shoes conformingly shaped to the pillars on which they ride. The guide shoes maintain the horizontal disposition .of the carriage and guide and stabilize the vertical motion.

To provide added rigidityv for the front frame 36, which supports the carriage 4, the pillars 38 are provided at their lower extremities with horizontal legs 58 extending forwardly and rearwardly. Each pillar 38 is To enable the drill assembly to be moved easily from one location to another, it is provided with an axle 66 extending transversely through thelower ends of the posts 60 having wheels 68 secured to its opposite extremities.

It will be appreciated that a drilling assembly in accordance with the present invention, provides a particularly stable drilling platform in which the opportunity for the drilling tool to become mislaigned is substantially eliminated. This desirable result is contributed to by the provision of the side arms and support members on the carriage whichprevent vertical displacement of 1 the drill relative to the carriage. In addition, the spaced apart points of connection of the shaft to the traveling members carried by the first and second threaded rods provides rigid lateral support for the drill so that play from side to side is also substantially eliminated. The general rigidity of the overall structure is enhanced by the bracing to the font frame provided by the rear posts and their connecting brace members.

Although the invention has been described with reference to one preferred embodiment, it will be appreciated by those skilled in the art that variations, modifications and other changes may be made without departing from the spirit of the invention herein described.

I claim:

l. A drill assembly comprising, a

an upright, rigid framework adapted to rest upon the ground,

a carriage connected with said framework for vertical motion relative thereto, said carriage including,

base means extending generally horizontally in a first direction forwardly from said framework,

a threaded rod rotatably mounted adjacent its extremities on said base means, said rod extending generally horizontally in a transverse, second direction perpendicular to said first direction,

a traveling member threadedly mounted on said rod moveable transversely therealong between said arms,

agenerally horizontal shaft fixedly connected with said traveling member extending forwardly therefrom,

means connected with said framework and said carriage for selectively'moving said carriage vertically of said framework,

a drill motor adapted to have a drill rod mounted thereto, 7 means connecting said drill motor with the forward end of said shaft; and r generally horizontal supportmeans connected with said base means extending transversely of said support means contacting the upper and lower surfaces of said shaft to enable horizontal traversing motion thereof while supporting said shaft against vertical motion relative to said carriage. thereby providing a vertically stable support for said drill motor. e 2. A drill assembly comprising,

an upright, rigid framework adapted to rest upon the ground, v

a carriage connected with said framework for vertical motion relative thereto, said carriage including,

a pair of arms connected in spaced opposed relation extending generally horizontally in a first direction frowardly from said framework,

a threaded rod rotatably connected adjacent its extremities with said arms, said rod extending generally horizontally in a transverse, second direction perpendicular to said first direction,

a traveling member threadedly mounted on said rod moveable transversely therealong between said arms, v I

a generally horizontal shaft fixedly connected with said traveling member extending forwardly therefrom, a

means connected with said framework and said carriage for selectively moving said carriage vertically of said framework,

a drill motor having,

a drill rod extending from said drill motor,

connecting means connecting said drill motor with the forward end of said shaft; and

two generally horizontal support members connected with said arms extending transversely therebetween, said support members contacting the upper and lower surfaces of said shaft to enable'horizontal traversing motion thereof while supporting said' shaft against vertical motion relative to said-carriage, thereby providing a vertically stable support for said drill motor. '3. A drill assembly comprising, an upright, rigid framework adapted to rest upon the ground, I a carriage connected with said framework for vertical motion relative thereto, said carriage including, two arms connected in spaced opposed relation extending generally horizontally in a first direction forwardly from said framework, a firs'tthreaded rod rotatably connected adjacent its extremities with said arms, said rod extending generally horizontally in a transverse, second direction perpendicular to said first direction, a first traveling member threadedly mounted on said rod moveable transversely therealong between said arms, a generally horizontal shaft fixedly connected with said traveling member extending forwardly therefrom,

a second threaded rod rotatably connected adjacent its extremities with said arms extending horizontally and spaced forwardly of said first threaded rod in'p'arallel relation thereto,

' a second traveling member threadedly engaging said second rod for motion transversely therealong between said arms, said second traveling member being transversely aligned with said'first traveling member, said second traveling member fixedly secured to said shaft,

means connected with said framework and said carriage for selectively moving said'carriage vertically of said framework,

a drill motor having, I

a drill rod extending from said drill motor,

connecting means connecting said drill motor wit the forward end of said shaftr'and drive means connecting said first and second threaded rods for coordinating the rotation of said rods so that said first and second traveling members maintain transversely aligned parallel relation as said traveling members move along said threaded rods, said traveling members and said threaded rods providing spaced rigid support for said shaft against pivoting motion in the horizontal plane. 1

4. A drill assembly as defined in claim 2, further including,

a second threaded rod rotatably connected adjacent its extremities with said arms extending horizontally and spaced forwardly of said first threaded rod in parallel relation thereto,

a second traveling member threadedly engaging said second rod for motion transversely ther'ealong between said arms, said second traveling member being transversely aligned with said first traveling member, said second traveling member fixedly secured to said shaft; and

an adjustable clamp connected with said shaft for selectively lockingsaid axle in any selected position.

7. A drill assembly as defined in claim 4, wherein said 5 means for movingsaid-carriage vertically of said framedrive means connecting said first and second threaded rods for coordinating the rotation of said rods so that said first and second traveling members maintain transversely aligned parallel relation as said traveling members move on said rods, said traveling members and said threaded rods providing spaced rigid support for said shaft against pivoting motion in the horizontal plane.

5. A drill assembly as defined in claim 4, wherein said connecting means enables pivoting motion of said drill motor relative to said carriage between positions in which said drill shaft is disposed vertically and other positions in which said drill shaft is disposed horizontally.

6. A drill assembly as definedin claim 5, whereinsaid shaft at the forward extremity thereof is provided with an open-ended, circular, internal bore and wherein said means for connecting said drill motor with said shaft includes,

a horizontal axle fixedly connected with said drill motor, said axle extending axially into said bore of said shaft, rotation about the axis of said axle and said shaft causing motion of said drill rod between the horizontal and vertical positions thereof; and

work further includes,

a vertical, third threaded rod having its upper and lower extremitiesrotatably connected with said framework,

a transversely extending cross memberfixedly connected between said arms of said carriage spaced rearwardly of said first threaded rod, said cross member having a vertically extending threaded opening threadedly engaging'said third threaded rod whereby rotation of said third rod causes vertical motion of said carriage,

guide means connected withsaid carriage and said frame for guiding said carriage in a predetermined vertical path relative to said frame while maintaining the horizontal disposition of said arms and a motor connected with said third threaded rod for selective rotation thereof in opposite directions to raise and lower said carriage.

8. A drill assembly as defined in claim 7, wherein said guide means further includes,

two spaced, opposed, vertically extending pillars po- 1 sitioned adjacent and on opposite sides of said third threaded rod; and

two vertically extending guide shoes fixedly secured to said arms extending outwardly therefrom in opposite directions, said guide shoes shaped to conformingly engageadjacent portions of said pillars to maintain the horizontal disposition of said arms while said pillars function as tracks guiding said carriage for vertical motion.

9. A drill assembly as defined in claim 8, wherein said framework further includes, ground engaging legs secured to the lower extremities of saidpillars extending rearwardly therefrom in an opposite direction from said carriage; and brace structure connecting the upper end extremities of said pillars with the rearward extremities of said legs to provide rigid support for said pillars. 

1. A drill assembly comprising, an upright, rigid framework adapted to rest upon the ground, a carriage connected with said framework for vertical motion relative thereto, said carriage including, base means extending generally horizontally in a first direction forwardly from said framework, a threaded rod rotatably mounted adjacent its extremities on said base means, said rod extending generally horizontally in a transverse, second direction perpendicular to said first direction, a traveling member threadedly mounted on said rod moveable transversely therealong between said arms, a generally horizontal shaft fixedly connected with said traveling member extending forwardly therefrom, means connected with said framework and said carriage for selectively moving said carriage vertically of said framework, a drill motor adapted to have a drill rod mounted thereto, means connecting said drill motor with the forward end of said shaft; and generally horizontal support means connected with said base means extending transversely of said support means contacting the upper and lower surfaces of said shaft to enable horizontal traversing motion thereof while supporting said shaft against vertical motion relative to said carriage, thereby providing a vertically stable support for said drill motor.
 2. A drill assembly comprising, an upright, rigid framework adapted to rest upon the ground, a carriage connected with said framework for vertical motion relative thereto, said carriage including, a pair of arms connected in spaced opposed relation extending generally horizontally in a first direction frowardly from said framework, a threaded rod rotatably connected adjacent its extremities with said arms, said rod extending generally horizontally in a transverse, second direction perpendicular to said first direction, a traveling member threadedly mounted on said rod moveable transversely therealong between said arms, a generally horizontal shaft fixedly connected with said traveling member extending forwardly therefrom, means connected with said framework and said carriage for selectively moving said carriage vertically of said framework, a drill motor having, a drill rod extending from said drill motor, connecting means connecting said drill motor with the forward end of said shaft; and two generally horizontal support members connected with said arms extending transversely therebetween, said support members contacting the upper and lower surfaces of said shaft to enable horizontal traversing motion thereof while supporting said shaft against vertical motion relative to said carriage, thereby providing a vertically stable support for said drill motor.
 3. A drill assembly comprising, an upright, rigid framework adapted to rest upon the ground, a carriage connected with said framework for vertical motion relative thereto, said carriage including, two arms connected in spaced opposed relation extending generally horizontally in a first direction forwardly from said framework, a first threaded rod rotatably connected adjacent its extremities with said arms, said rod extending generally horizontally in a transvErse, second direction perpendicular to said first direction, a first traveling member threadedly mounted on said rod moveable transversely therealong between said arms, a generally horizontal shaft fixedly connected with said traveling member extending forwardly therefrom, a second threaded rod rotatably connected adjacent its extremities with said arms extending horizontally and spaced forwardly of said first threaded rod in parallel relation thereto, a second traveling member threadedly engaging said second rod for motion transversely therealong between said arms, said second traveling member being transversely aligned with said first traveling member, said second traveling member fixedly secured to said shaft, means connected with said framework and said carriage for selectively moving said carriage vertically of said framework, a drill motor having, a drill rod extending from said drill motor, connecting means connecting said drill motor with the forward end of said shaft; and drive means connecting said first and second threaded rods for coordinating the rotation of said rods so that said first and second traveling members maintain transversely aligned parallel relation as said traveling members move along said threaded rods, said traveling members and said threaded rods providing spaced rigid support for said shaft against pivoting motion in the horizontal plane.
 4. A drill assembly as defined in claim 2, further including, a second threaded rod rotatably connected adjacent its extremities with said arms extending horizontally and spaced forwardly of said first threaded rod in parallel relation thereto, a second traveling member threadedly engaging said second rod for motion transversely therealong between said arms, said second traveling member being transversely aligned with said first traveling member, said second traveling member fixedly secured to said shaft; and drive means connecting said first and second threaded rods for coordinating the rotation of said rods so that said first and second traveling members maintain transversely aligned parallel relation as said traveling members move on said rods, said traveling members and said threaded rods providing spaced rigid support for said shaft against pivoting motion in the horizontal plane.
 5. A drill assembly as defined in claim 4, wherein said connecting means enables pivoting motion of said drill motor relative to said carriage between positions in which said drill shaft is disposed vertically and other positions in which said drill shaft is disposed horizontally.
 6. A drill assembly as defined in claim 5, wherein said shaft at the forward extremity thereof is provided with an open-ended, circular, internal bore and wherein said means for connecting said drill motor with said shaft includes, a horizontal axle fixedly connected with said drill motor, said axle extending axially into said bore of said shaft, rotation about the axis of said axle and said shaft causing motion of said drill rod between the horizontal and vertical positions thereof; and an adjustable clamp connected with said shaft for selectively locking said axle in any selected position.
 7. A drill assembly as defined in claim 4, wherein said means for moving said carriage vertically of said framework further includes, a vertical, third threaded rod having its upper and lower extremities rotatably connected with said framework, a transversely extending cross member fixedly connected between said arms of said carriage spaced rearwardly of said first threaded rod, said cross member having a vertically extending threaded opening threadedly engaging said third threaded rod whereby rotation of said third rod causes vertical motion of said carriage, guide means connected with said carriage and said frame for guiding said carriage in a predetermined vertical path relative to said frame while maintaining the horizontal disposition of said arms; aNd a motor connected with said third threaded rod for selective rotation thereof in opposite directions to raise and lower said carriage.
 8. A drill assembly as defined in claim 7, wherein said guide means further includes, two spaced, opposed, vertically extending pillars positioned adjacent and on opposite sides of said third threaded rod; and two vertically extending guide shoes fixedly secured to said arms extending outwardly therefrom in opposite directions, said guide shoes shaped to conformingly engage adjacent portions of said pillars to maintain the horizontal disposition of said arms while said pillars function as tracks guiding said carriage for vertical motion.
 9. A drill assembly as defined in claim 8, wherein said framework further includes, ground engaging legs secured to the lower extremities of said pillars extending rearwardly therefrom in an opposite direction from said carriage; and brace structure connecting the upper end extremities of said pillars with the rearward extremities of said legs to provide rigid support for said pillars. 